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WU_E_INSTALLATION_RESULTS_UNKNOWN_VERSION
WU_E_INSTALLATION_RESULTS_UNKNOWN_VERSION means Windows Update found installation-result data in the registry, but the format version was not recognized. The update may have run; the problem is reading back its recorded result.
What to do
- Confirm the actual package state through the update history, servicing records, and logs before attempting another install.
- Check for an interrupted OS upgrade, component servicing failure, or unsupported tooling that might have written incompatible state.
- Do not assume the update is absent merely because the result record cannot be parsed.
Microsoft: IUpdateInstaller::Install
Microsoft: Windows Update log files
Microsoft: Windows Update error reference
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